[Pw_forum] How simulate atoms of same element with different oxidation number in compounds?

[max]

Dear,

I appreciate your recommendation, I'll continue with these guidelines.

2017-04-17 23:57 GMT-04:00 Marton <vormar at gmail.com>:

> Hi Máximo,
>
> In my experience, especially when dealing with spinel LiMn2O4, you also
> need to address the Jahn-Teller instability induced by Mn3+. If you
> slightly distort the spinel unit cell then the two different Mn sites
> (formally 3+ and 4+) will naturally emerge during relaxation (of course,
> you need the right level of theory as Nicola said): Mn3+ sites will be in a
> tetragonally distorted octahedral environment and Mn4+ sites will be in a
> more octahedral environment. If you start from a high-symmetry unit cell,
> you can also try to break the initial high symmetry of the charge/spin
> density by manually distinguishing between the two Mn sites: just name one
> type of Mn let's say Mn1 and the other one Mn2 and then use the same
> pseudopotential for both. Then, you can initialize the magnetization to a
> different value for the two different species.
>
> HTH
> Marton Voros
>
> --
> Materials Science Division
> Argonne National Laboratory
>
> On Mon, Apr 17, 2017 at 8:45 AM, Nicola Marzari <nicola.marzari at epfl.ch>
> wrote:
>
>>
>>
>> Indeed! At the very least, use DFT+U, and/or explore
>> hybrid functionals. DFT+U+V seems to be very promising,
>> but it's not in the code there.
>>
>>                                 nicola
>>
>>
>>
>> On 17/04/2017 15:36, Ary Junior wrote:
>> > Hi,
>> >
>> > Search for "constrained DFT" and you will find some documents that would
>> > be useful for you, like this one
>> >
>> > http://theossrv1.epfl.ch/Main/OxidationStates
>> >
>> > Ary Ferreira
>> >
>> > FAPESP postdoctoral fellow
>> > UFSCar - Brazil
>> >
>> > On Sun, Apr 16, 2017 at 1:06 PM, Máximo Ramírez <aquiles011 at gmail.com
>> > <mailto:aquiles011 at gmail.com>> wrote:
>> >
>> >     Dear,
>> >
>> >     I'm interested in simulate metal oxide that has two different
>> >     valence state (oxidation number) in the same compound.
>> >
>> >     For example:
>> >
>> >     Is well-known from experimental results that spinel compounds have
>> >     Mn ions with valence +3 and +4, LiMn3+Mn4+O4.
>> >
>> >     How can I simulate this behavior in QE?
>> >
>> >     And also, How can I post-process the two atoms like were different?
>> >
>> >     Thank in Advance!
>> >
>> >
>> >     <https://www.researchgate.net/publication/245108648_
>> Factors_affecting_Li_mobility_in_spinel_LiMn_2O_4-A_first-pr
>> inciples_study_by_GGA_and_GGA_U_methods>
>> >     --
>> >     Sincerely,
>> >
>> >     Máximo Ramírez
>> >     Research Assistant
>> >     Nanotechnology Laboratory, INTEC
>> >     Santo Domingo, Dominican Republic
>> >
>> >
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>> >
>> >
>> >
>> > --
>> > http://lattes.cnpq.br/8221674673413336
>> >
>> >
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>>
>> --
>> ----------------------------------------------------------------------
>> Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL
>> Director, National Centre for Competence in Research NCCR MARVEL, EPFL
>> http://theossrv1.epfl.ch/Main/Contact http://nccr-marvel.ch/en/project
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